METHOD AND APPARATUS TO ENABLE CSI REPORTING IN WIRELESS COMMUNICATION SYSTEMS
A method of a user equipment (UE) in a wireless communication system is provided. The method comprises: receiving, from a base station (BS), CSI feedback configuration information; and deriving, based on the CSI feedback configuration information, the CSI feedback including a precoding matrix indicator (PMI), transmitting, to the BS via an uplink channel, the CSI feedback including the PMI, wherein, for each layer l=1, 2, . . . , v, the PMI indicates K NZ,l non-zero (NZ) coefficients out of a total of 2LM v coefficients, each of which is represented as c l,i,m =p l,i,m (1) p l,i,m (2) ϕ l,i,m , the K NZ,l NZ coefficients are partitioned into two groups (G 0 and G 1 ), and for each group G r , rϵ{0,1}, one p l,i,m (1) value is indicated, where v is a rank value, p l,i,m (1) is a first amplitude coefficient, p l,i,m (2) is a second amplitude coefficient, and ϕ l,i,m is a phase coefficient.
1 . A user equipment (UE) for a channel state information (CSI) feedback in a wireless communication system, the UE comprising:
a transceiver configured to receive, from a base station (BS), CSI feedback configuration information; and
a processor operably connected to the transceiver, the processor configured to derive, based on the CSI feedback configuration information, the CSI feedback including a precoding matrix indicator (PMI),
wherein the transceiver is further configured to transmit, to the BS via an uplink channel, the CSI feedback including the PMI,
wherein, for each layer l=1, 2, . . . , v, the PMI indicates K NZ,l non-zero (NZ) coefficients out of a total of 2LM v coefficients, each of which is represented as c l,i,m =p l,i,m (1) p l,i,m (2) ϕ l,i,m the K NZ,l NZ coefficients are partitioned into two groups (G 0 and G 1 ), and for each group G r , rϵ{0,1}, one p l,i,m (1) value is indicated, where v is a rank value, p l,i,m (1) is a first amplitude coefficient, p l,i,m (2) is a second amplitude coefficient, and ϕ l,i,m is a phase coefficient.
2 . The UE of claim 1 , wherein:
the total of 2LM v coefficients forms a 2L×M v coefficient matrix C l comprising 2L rows and M v columns;
the group G 0 comprises all coefficients c l,i,m with an index iϵ{0,1, . . . ,L−1};
the group G 1 comprises all coefficients c l,i,m with an index iϵ{L, L+1, . . . ,2L−1}; and
the one p l,i,m (1) value indicated for the group G r is given by p l,i,m (1) =p l,r (1) , where
r
=
⌊
i
L
⌋
.
3 . The UE of claim 2 , wherein the PMI includes amplitude coefficient indicators i 2,3,l and i 2,4,l for first amplitude coefficients and second amplitude coefficients, respectively, given by:
i 2,3,l =[ k l,0 (1) k l,1 (1) ],
i 2,4,l =[ k l,0 (2) . . . k l,M-1 (2) ],
k l,m (2) =[ k l,0,m (2) . . . k l,2L-1,m (2) ],
k l,r (1) ϵ{1, . . . ,15}, and
k l,i,m (2) ϵ{1, . . . ,7},
where the first amplitude coefficients and the second amplitude coefficients are represented by:
p l (1) =[ p l,0 (1) p l,1 (1) ],
p l (2) =[ p l,0 (2) . . . p l,M-1 (2) ], and
p l,m (2) =[ p l,0,m (2) . . . p l,2L-1,m (2) ],
a mapping from k l,r (1) to the first amplitude coefficient p l,r (1) i s given by:
k l,r (1)
p l,r (1)
0
Reserved
1
1
128
2
(
1
8192
)
1
/
4
3
1
8
4
(
1
2048
)
1
/
4
5
1
2
8
6
(
1
512
)
1
/
4
7
(
1
128
)
1
/
4
8
1
8
9
(
1
128
)
1
/
4
10
(
1
32
)
1
/
4
11
1
2
12
(
1
8
)
1
/
4
13
1
2
14
(
1
2
)
1
/
4
15
1
and a mapping from k l,i,m (2) to the second amplitude coefficient p l,i,m (2) is given by:
k l,i,m (2)
p l,i,m (2)
0
1
8
2
1
1
8
2
1
4
2
3
1
4
4
1
2
2
5
1
2
6
1
2
7
1
4 . The UE of claim 2 , wherein, for each layer l=1, . . . ,v:
the processor is further configured to determine a strongest coefficient indicator i 1,8,l indicating an index (i* l , m* l ) that jointly indicates:
a location of a strongest coefficient c l,i* l ,m* l =1, and
a first amplitude coefficient indicator k l,r* (1) indicating p l,r* (1) =1 for the group G r* to which the strongest coefficient belongs, where
r
*
=
⌊
i
l
*
L
⌋
;
and
the transceiver is further configured to transmit, to the BS, the CSI feedback including the PMI that includes the determined strongest coefficient indicator i 1,8,l .
5 . The UE of claim 4 , wherein, for each layer l=1, . . . , v:
the processor is further configured to:
determine another group G r , where r≠r*; and
determine a first amplitude coefficient indicator k l,r* (1) indicating p l,r* (1) for the other group G r ; and
the transceiver is further configured to transmit, to the BS, the CSI feedback including the PMI that includes i 2,3,l indicating the first amplitude coefficient indicator for the other group.
6 . The UE of claim 5 , wherein the transceiver is further configured to transmit, using the CSI feedback, the PMI including, for each layer l=1, . . . , v:
one indicator for the first amplitude coefficient associated with the other group G r ;
K NZ,l −1 indicators for the second amplitude coefficients; and
K NZ,l −1 indicators for phase coefficients,
where for remaining 2LM v −K NZ,l coefficients, the second amplitude coefficients and the phase coefficients are set to p l,i,m (2) =ϕ l,i,m =0.
7 . The UE of claim 2 , wherein the PMI further includes indicators for a spatial domain (SD) basis matrix A and a frequency domain (FD) basis matrix B l for each layer l=1, . . . , v, and
wherein:
a precoding matrix for each FD unit of a total number (N 3 ) of FD units is determined by columns of
W
=
1
v
[
W
1
W
2
…
W
v
]
,
where
W
l
=
[
A
0
0
A
]
C
l
B
l
H
=
[
∑
i
=
0
L
-
1
a
i
∑
m
=
0
M
v
-
1
C
l
,
i
,
m
(
b
l
,
m
H
)
∑
i
=
0
L
-
1
a
i
∑
m
=
0
M
v
-
1
C
l
,
i
+
L
,
m
(
b
l
,
m
H
)
]
=
[
∑
i
=
0
L
-
1
a
i
p
l
,
0
(
1
)
∑
m
=
0
M
v
-
1
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
(
b
l
,
m
H
)
∑
i
=
0
L
-
1
a
i
p
l
,
1
(
1
)
∑
m
=
0
M
v
-
1
p
l
,
i
+
L
,
m
(
2
)
ϕ
l
,
i
+
L
,
m
(
b
l
,
m
H
)
]
is a pre-coding matrix for layer l, whose t-th column is a pre-coding matrix for FD unit t and is given by
W
t
l
=
1
N
1
N
2
γ
t
,
l
[
∑
i
=
0
L
-
1
a
i
p
l
,
0
(
1
)
∑
m
=
0
M
v
-
1
y
t
,
l
(
m
)
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
∑
i
=
0
L
-
1
a
i
p
l
,
1
(
1
)
∑
m
=
0
M
v
-
1
y
t
,
l
(
m
)
p
l
,
i
+
L
,
m
(
2
)
ϕ
l
,
i
+
L
,
m
]
,
where
γ
t
,
l
=
∑
i
=
0
2
L
-
1
(
p
l
,
⌊
i
L
⌋
(
1
)
)
2
∑
m
=
0
M
-
1
y
t
,
l
(
m
)
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
2
normalizes t-th column to norm one;
A=[a 0 a 1 . . . a L-1 ], a i =v m 1 (i) , v m 1 (i) is a N 1 N 2 ×1 column vector for SD antenna ports where N 1 and N 2 are number of antenna ports, respectively, with a same antenna polarization in a first and a second dimensions of a two-dimensional dual-polarized channel state information-reference signal (CSI-RS) antenna ports at the BS;
B l =[b l,0 b l,1 . . . b l,M v -1 ], b l,m is a N 3 ×1 column vector for FD units, and y t,l (m) =the t-th entry of m-th FD basis vector b l,m ; and
a number (L) of column vectors for the SD antenna ports, a number (M v ) of column vectors for the FD units, and the total number (N 3 ) of the FD units are configured via higher layer signaling.
8 . A base station (BS) in a wireless communication system, the BS comprising:
a transceiver configured to:
transmit, to a user equipment (UE), CSI feedback configuration information; and
receive, from the UE via an uplink channel, a CSI feedback including a precoding matrix indicator (PMI),
wherein, for each layer l=1, 2, . . . , v, the PMI indicates K NZ,l non-zero (NZ) coefficients out of a total of 2 LM v coefficients, each of which is represented as c l,i,m =p l,i,m (1) p l,i,m (2) ϕ l,i,m , the K NZ,l NZ coefficients are partitioned into two groups (G 0 and G 1 ), and for each group G r , rϵ{0,1}, one p l,i,m (1) value is indicated, where v is a rank value, p l,i,m (1) is a first amplitude coefficient, p l,i,m (2) is a second amplitude coefficient, and ϕ l,i,m is a phase coefficient, and
wherein the CSI feedback including the PMI is based on the CSI feedback configuration information.
9 . The BS of claim 8 , wherein:
the total of 2LM v coefficients forms a 2L×M v coefficient matrix C l comprising 2L rows and M v columns;
the group G 0 comprises all coefficients c l,i,m with an index iϵ{0,1, . . . ,L−1};
the group G 1 comprises all coefficients c l,i,m with an index iϵ{L, L+1, . . . ,2L−1}; and
the one p l,i,m (1) value indicated for the group G r is given by p l,i,m (1) =p l,r (1) , where
r
=
⌊
i
L
⌋
.
10 . The BS of claim 9 , wherein the PMI includes amplitude coefficient indicators i 2,3,l and i 2,4,l for first amplitude coefficients and second amplitude coefficients, respectively, given by:
i 2,3,l =[ k l,0 (1) k l,1 (1) ],
i 2,4,l =[ k l,0 (2) . . . k l,M-1 (2) ],
k l,m (2) =[ k l,0,m (2) . . . k l,2L-1,m (2) ],
k l,r (1) ϵ{1, . . . ,15}, and
k l,i,m (2) ϵ{1, . . . ,7},
where the first amplitude coefficients and the second amplitude coefficients are represented by:
p l (1) =[ p l,0 (1) p l,1 (1) ],
p l (2) =[ p l,0 (2) . . . p l,M-1 (2) ], and
p l,m (2) =[ p l,0,m (2) . . . p l,2L-1,m (2) ],
a mapping from k l,r (1) to the first amplitude coefficient p l,r (1) i s given by:
k l,r (1)
p l,r (1)
0
Reserved
1
1
128
2
(
1
8192
)
1
/
4
3
1
8
4
(
1
2048
)
1
/
4
5
1
2
8
6
(
1
512
)
1
/
4
7
1
4
8
(
1
128
)
1
/
4
9
1
8
10
(
1
32
)
1
/
4
11
1
2
12
(
1
8
)
1
/
4
13
1
2
14
(
1
2
)
1
/
4
15
1
and a mapping from k l,i,m (2) to the second amplitude coefficient p l,i,m (2) is given by:
k l,i,m (2)
p l,i,m (2)
0
1
8
2
1
1
8
2
1
4
2
3
1
4
4
1
2
2
5
1
2
6
1
2
7
1
11 . The BS of claim 9 , wherein, for each layer l=1, . . . ,v, the transceiver is further configured to receive, from the UE, the CSI feedback including the PMI that includes a strongest coefficient indicator i 1,8,l , and
wherein the strongest coefficient indicator i 1,8,l indicates an index (i* l ,m* l ) that jointly indicates:
a location of a strongest coefficient c l,i* l ,m* l =1, and
a first amplitude coefficient indicator k l,r* (1) indicating p l,r* (1) =1 for the group G r* to which the strongest coefficient belongs, where
r
*
=
⌊
i
l
*
L
⌋
.
12 . The BS of claim 11 , wherein, for each layer l=1, . . . ,v, the transceiver is further configured to receive, from the UE, the CSI feedback including the PMI that includes i 2,3,l indicating a first amplitude coefficient indicator k l,r (1) for another group G r , and wherein r≠r*; and the first amplitude coefficient indicator k l,r (1) indicates p l,r (1) for the other group G r .
13 . The BS of claim 12 , wherein the transceiver is further configured to receive, using the CSI feedback, the PMI including, for each layer l=1, . . . , v:
one indicator for the first amplitude coefficient associated with the other group G r ;
K NZ,l −1 indicators for the second amplitude coefficients; and
K NZ,l −1 indicators for the phase coefficients,
where for remaining 2LM v −K NZ,l coefficients, the second amplitude coefficients and the phase coefficients are set to p l,i,m (2) =ϕ l,i,m = 0 .
14 . The BS of claim 9 , wherein the PMI further includes indicators for a spatial domain (SD) basis matrix A and a frequency domain (FD) basis matrix B 1 for each layer l=1, . . . , v, and
wherein:
a precoding matrix for each FD unit of a total number (N 3 ) of FD units is determined by columns of
W
=
1
v
[
W
1
W
2
…
W
v
]
,
where
W
l
=
[
A
0
0
A
]
C
l
B
l
H
=
[
∑
i
=
0
L
-
1
a
i
∑
m
=
0
M
v
-
1
C
l
,
i
,
m
(
b
l
,
m
H
)
∑
i
=
0
L
-
1
a
i
∑
m
=
0
M
v
-
1
C
l
,
i
+
L
,
m
(
b
l
,
m
H
)
]
=
[
∑
i
=
0
L
-
1
a
i
p
l
,
0
(
1
)
∑
m
=
0
M
v
-
1
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
(
b
l
,
m
H
)
∑
i
=
0
L
-
1
a
i
p
l
,
1
(
1
)
∑
m
=
0
M
v
-
1
p
l
,
i
+
L
,
m
(
2
)
ϕ
l
,
i
+
L
,
m
(
b
l
,
m
H
)
]
is a pre-coding matrix for layer l, whose t-th column is a pre-coding matrix for FD unit t and is given by
W
t
l
=
1
N
1
N
2
γ
t
,
l
[
∑
i
=
0
L
-
1
a
i
p
l
,
0
(
1
)
∑
m
=
0
M
v
-
1
y
t
,
l
(
m
)
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
∑
i
=
0
L
-
1
a
i
p
l
,
1
(
1
)
∑
m
=
0
M
v
-
1
y
t
,
l
(
m
)
p
l
,
i
+
L
,
m
(
2
)
ϕ
l
,
i
+
L
,
m
]
,
where
γ
t
,
l
=
∑
i
=
0
2
L
-
1
(
p
l
,
⌊
i
L
⌋
(
1
)
)
2
∑
m
=
0
M
-
1
y
t
,
l
(
m
)
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
2
normalizes t-th column to norm one;
A=[a 0 a 1 . . . a L-1 ], a i =v m 1 (i) , v m 1 (i) is a N 1 N 2 ×1 column vector for SD antenna ports where N 1 and N 2 are number of antenna ports, respectively, with a same antenna polarization in a first and a second dimensions of a two-dimensional dual-polarized channel state information-reference signal (CSI-RS) antenna ports at the BS;
B l =[b l,0 b l,1 . . . b l,M v -1 ], b l,m is a N 3 ×1 column vector for FD units, and y t,l (m) =the t-th entry of m-th FD basis vector b l,m ; and
a number (L) of column vectors for the SD antenna ports, a number (M v ) of column vectors for the FD units, and the total number (N 3 ) of the FD units are configured via higher layer signaling.
15 . A method of a user equipment (UE) in a wireless communication system, the method comprising:
receiving, from a base station (BS), CSI feedback configuration information;
deriving, based on the CSI feedback configuration information, the CSI feedback including a precoding matrix indicator (PMI); and
transmitting, to the BS via an uplink channel, the CSI feedback including the PMI,
wherein, for each layer l=1, 2, . . . , v, the PMI indicates K NZ,l non-zero (NZ) coefficients out of a total of 2 LM v coefficients, each of which is represented as c l,i,m =p l,i,m (1) p l,i,m (2) ϕ l,i,m , the K NZ,l NZ coefficients are partitioned into two groups (G 0 and G 1 ), and for each group G r , rϵ{0,1}, one p l,i,m (1) value is indicated, where v is a rank value, p l,i,m (1) is a first amplitude coefficient, p l,i,m (2) is a second amplitude coefficient, and ϕ l,i,m is a phase coefficient.
16 . The method of claim 15 , wherein:
the total of 2LM v coefficients forms a 2L×M v coefficient matrix C l comprising 2L rows and M v columns;
the group G 0 comprises all coefficients c l,i,m with an index iϵ{0,1, . . . ,L−1};
the group G 1 comprises all coefficients c l,i,m with an index iϵ{L, L+1, . . . ,2L−1};
the one p l,i,m (1) value indicated for the group G r is given by p l,i,m (1) =p l,r (1) , where
r
=
⌊
i
L
⌋
;
and
the PMI includes amplitude coefficient indicators i 2,3,l and i 2,4,l for first amplitude coefficients and second amplitude coefficients, respectively, given by:
i 2,3,l =[ k l,0 (1) k l,1 (1) ],
i 2,4,l =[ k l,0 (2) . . . k l,M-1 (2) ],
k l,m (2) =[ k l,0,m (2) . . . k l,2L-1,m (2) ],
k l,r (1) ϵ{1, . . . ,15}, and
k l,i,m (2) ϵ{1, . . . ,7},
where the first amplitude coefficients and the second amplitude coefficients are represented by:
p l (1) =[ p l,0 (1) p l,1 (1) ],
p l (2) =[ p l,0 (2) . . . p l,M-1 (2) ], and
p l,m (2) =[ p l,0,m (2) . . . p l,2L-1,m (2) ],
a mapping from k l,r (1) to the first amplitude coefficient p l,r (1) i s given by:
k l,r (1)
p l,r (1)
0
Reserved
1
1
128
2
(
1
8192
)
1
/
4
3
1
8
4
(
1
2048
)
1
/
4
5
1
2
8
6
(
1
512
)
1
/
4
7
1
4
8
(
1
128
)
1
/
4
9
1
8
10
(
1
32
)
1
/
4
11
1
2
12
(
1
8
)
1
/
4
13
1
2
14
(
1
2
)
1
/
4
15
1
and a mapping from k l,i,m (2) to the second amplitude coefficient p l,i,m (2) is given by:
k l,i,m (2)
p l,i,m (2)
0
1
8
2
1
1
8
2
1
4
2
3
1
4
4
1
2
2
5
1
2
6
1
2
7
1
17 . The method of claim 16 , wherein, for each layer l=1, . . . , v, further comprising:
determining a strongest coefficient indicator i 1,8,l indicating an index (i* l , m* l ) that jointly indicates:
a location of a strongest coefficient c l,i* l ,m* l =1, and
a first amplitude coefficient indicator k l,r* (1) indicating p l,r* (1) =1 for the group G r* to which the strongest coefficient belongs, where
r
*
=
⌊
i
l
*
L
⌋
;
and
which the strongest coefficient belongs, where and transmitting, to the BS, the CSI feedback including the PMI that includes the determined strongest coefficient indicator i 1,8,l .
18 . The method of claim 17 , wherein, for each layer l=1, . . . , v, further comprising:
determining another group G r , where r≠r*;
determining a first amplitude coefficient indicator k l,r (1) indicating p l,r (1) for the other group G r ; and
transmitting, to the BS, the CSI feedback including the PMI that includes i 2,3,l indicating the first amplitude coefficient indicator for the other group.
19 . The method of claim 15 , further comprising transmitting, using the CSI feedback, the PMI including, for each layer l=1, . . . , v:
one indicator for the first amplitude coefficient associated with the other group G r ;
K NZ,l −1 indicators for the second amplitude coefficients; and
K NZ,l −1 indicators for phase coefficients,
where for remaining 2LM v −K NZ,l coefficients, the second amplitude coefficients and the phase coefficients are set to p l,i,m (2) =ϕ l,i,m =0.
20 . The method of claim 16 , wherein the PMI further includes indicators for a spatial domain (SD) basis matrix A and a frequency domain (FD) basis matrix B l for each layer l=1, . . . , v, and
wherein:
a precoding matrix for each FD unit of a total number (N 3 ) of FD units is determined by columns of
W
=
1
v
[
W
1
W
2
…
W
v
]
,
where
W
l
=
[
A
0
0
A
]
C
l
B
l
H
=
[
∑
i
=
0
L
-
1
a
i
∑
m
=
0
M
v
-
1
C
l
,
i
,
m
(
b
l
,
m
H
)
∑
i
=
0
L
-
1
a
i
∑
m
=
0
M
v
-
1
C
l
,
i
+
L
,
m
(
b
l
,
m
H
)
]
=
[
∑
i
=
0
L
-
1
a
i
p
l
,
0
(
1
)
∑
m
=
0
M
v
-
1
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
(
b
l
,
m
H
)
∑
i
=
0
L
-
1
a
i
p
l
,
1
(
1
)
∑
m
=
0
M
v
-
1
p
l
,
i
+
L
,
m
(
2
)
ϕ
l
,
i
+
L
,
m
(
b
l
,
m
H
)
]
is a pre-coding matrix for layer l, whose t-th column is a pre-coding matrix for FD unit t and is given by
W
t
l
=
1
N
1
N
2
γ
t
,
l
[
∑
i
=
0
L
-
1
a
i
p
l
,
0
(
1
)
∑
m
=
0
M
v
-
1
y
t
,
l
(
m
)
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
∑
i
=
0
L
-
1
a
i
p
l
,
1
(
1
)
∑
m
=
0
M
v
-
1
y
t
,
l
(
m
)
p
l
,
i
+
L
,
m
(
2
)
ϕ
l
,
i
+
L
,
m
]
,
where
γ
t
,
l
=
∑
i
=
0
2
L
-
1
(
p
l
,
⌊
i
L
⌋
(
1
)
)
2
∑
m
=
0
M
-
1
y
t
,
l
(
m
)
p
l
,
i
,
m
(
2
)
ϕ
l
,
i
,
m
2
normalizes t-th column to norm one;
A=[a 0 a 1 . . . a L-1 ], a i =v m 1 (i) , v m 1 (i) is a N 1 N 2 ×1 column vector for SD antenna ports where N 1 and N 2 are number of antenna ports, respectively, with a same antenna polarization in a first and a second dimensions of a two-dimensional dual-polarized channel state information-reference signal (CSI-RS) antenna ports at the BS;
B l =[b l,0 b l,1 . . . b l,M v -1 ], b l,m is a N 3 ×1 column vector for FD units, and y t,l (m) =the t-th entry of m-th FD basis vector b l,m ; and
a number (L) of column vectors for the SD antenna ports, a number (M v ) of column vectors for the FD units, and the total number (N 3 ) of the FD units are configured via higher layer signaling.